Rebuilding to a larger array?

Hi All.

We are currently running a RAID 5 configuration on one of our servers and each drive is 36.5GB. If we were to slowly replace/rebuild each drive with 70GB ones, will the array expand itself to the larger sized drive? Or would this have to be done using the array configuration software? The server is a HP Proliant ML370 G3.

Any thoughts would be much appreciated.

Jason